This invention relates to an elastomeric mounting and in particular, though not exclusively, to an elastomeric mounting suitable for use in providing a low frequency suspension for a vehicle cab. It relates also to a suspension system comprising a plurality of said mountings.
A vehicle cab suspension, especially a road vehicle cab suspension, usually is required, for operator comfort, to exhibit low frequency and low stiffness characteristics over a wide range of dynamic deflections under normal cab loading conditions. Elastomeric material commonly is used in seeking to meet this requirement and it is known to provide a vehicle cab suspension comprising a pair of tubular metal members arranged co-axially one within the other and interconnected by an annular element of elastomeric material bonded to the tubular members. The annular elastomeric element is orientated such that the normal load of the cab acts in a direction parallel with the longitudinal axis of the tubular members and in consequence vertical movement of the cab relative to the vehicle body is accommodated by shear deflection of the elastomeric material. While the resulting suspension can provide a satisfactory performance it suffers the disadvantage of needing to be of large dimensions in order to allow for the magnitude of shear deflection necessary to accommodate the desired large range of dynamic deflection under normal cab loading conditions. It also suffers the disadvantage of often requiring the provision of additional damping means and of not having a sufficiently great conical stiffness.